Filtration of liquid materials is required in many processes to remove impurities or other contaminants. Filtration is often accomplished by causing a liquid to flow through a filter material which causes the contaminants to be separated and to collect on or in the filter material. The liquid that is cleansed of the contaminants collected on or in the filter material is then directed to such uses and processes that can be carried out once the contaminants have been removed.
Over time as contaminants are removed they collect on the filter material and eventually restrict the flow of liquid therethrough. When this occurs, the filter material either needs to be changed or cleaned. This can be done in some arrangements by replacing the filter material with new material and the filtration process continues. Unfortunately in many such arrangements the filtration process and the flow of liquid must be interrupted while the filter material is replaced.
In other arrangements the filter material can be cleansed of contaminants so that the same material can continue to be used to filter the liquid. One approach to cleansing the filter material is to reverse the flow of liquid across the filter material from the direction of flow that normally occurs during removal of contaminants. This reversing of flow which is sometimes referred to as back flushing, operates to dislodge the contaminants that have been collected on the dirty side of the filter material. These contaminants once dislodged can settle or otherwise be directed away from the filter material a sufficient distance so that the contaminants will not rapidly collect on the filter material when the flow is returned to the normal direction. This approach provides the advantage that the filter material can be used for a longer period of time before it needs to be replaced.
Further in some arrangements, filter media in multiple filter element arrangements is provided so that the flow of filtered liquid can continue even during times that a filter element is being back flushed. This may be accomplished by continuing the flow of liquid in the filtering direction through one or more of the multiple filter elements while one or more other elements are subject to being back flushed. The periodic back flushing of respective filter elements at different times serves to keep the filter material from becoming restricted or blocked and helps to assure adequate liquid flow.
In some prior systems multi-element arrangements that provide the capability for back flushing have included fixed support structures for the filter elements and back flush structures within a filter vessel. These arrangements have included rigidly welded filter element support structures that are necessary to support and maintain the accurate position of the filter elements. This is sometimes necessary in high pressure, high flow filtration systems where the pressure that is exerted on the filter elements and other components would otherwise cause the filter elements or other structures to move, collapse or otherwise fail during use.
Filter structures that include such rigid elements can sometimes prevent ready access to components that periodically need maintenance or replacement. For example, in some arrangements the structures that facilitate back flushing and the flow of contaminants out of the filter vessel that have been dislodged from elements, may be obscured by the filtration and support structures. As a result when such items fail and become inoperable, they can be difficult to access for purposes of repair. This can result in extended periods of filter downtime. The filtered liquid required for the associated use is then not available, which causes the other industrial processes that depend on the filtered liquid to also be shut down. Considerable labor, effort and expense can also be necessary to repair and place such filtration systems back in operation.
Liquid filtration systems may benefit from improvements.